Systems and methods herein generally relate to printing systems that use liquid marking materials, and more particularly to methods and apparatuses for mitigating particulate settling in such liquid marking material handling systems.
When a printing device is not in use for extended periods of time (often greater than two weeks) marking material sedimentations can occur. The marking material sedimentation causes some elements in the marking engine to clog, which ultimately forces the customer to be down for long periods of time. Additionally, depending on the type of clogging and the location of the clog, the failure mode can be costly to repair, especially if the marking material sediment enters the marking engine head, filters, or other marking material handling elements.
For example, marking material clogging can occur in a sub-tank, along with the main tank. If a liquid marking material printing device is unused for a multi-week period, the sub-tank clogging can occur and ink replacement or cleaning can be required. Sub-tanks are above the printing device head and may cause liquid marking material to drop down to the head. Filters and valves between the sub-tank and the head may also get clogged during the purging sequence. When some printing machines are shut down and idle, there may no longer be any additional source of energy delivered to the machine, other than what is contained within the machine.
One type of liquid marking material printing system that frequently encounters problems with ink sedimentation is a magnetic ink character recognition (MICR) system. In MICR systems various tanks and sub-tanks are very sensitive to ink particulate settling issues, which can result in clogged filters, nozzles, jets, etc.